Chlorotic Ringspot and Decline of Ornamental Shamrock (Oxalis regnellii). D. L. Coyier, Research Plant Pathologist, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, Ornamental Plants Research Laboratory, Corvallis, OR 97330. Plant Dis. 65:275-276. . This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1981. DOI: 10.1094/PD-65-275.

Chlorotic ringspot and decline of shamrock, a new, presumably viral disease, caused serious losses in 1977-1978 in a Washington nursery. The causal agent was not mechanically transmissible to any of 24 plant hosts but was transmitted by root contact in 116 of 120 pairs (97%) of infected and healthy plants. Symptomatological evidence of transmission developed after 100 or more days of plant contact, in the absence of nematode or insect vectors of plant viruses. Judicious roguing of infected plants is a suggested control measure.